The present disclosure relates generally to a lubrication system for an internal combustion engine and, more particularly, to a dry sump lubrication system including an oil tank located outside of the engine crankcase.
Most production cars have a wet sump lubrication system, where the sump is an area below a crankshaft of the engine. In a “wet” sump, the lubricant such as oil is stored beneath the crankshaft in an oil pan. Typically, the oil pan needs to be large and deep enough to hold about four to six quarts of oil.
In a dry sump lubrication system, extra oil is stored in a tank outside the engine rather than in the oil pan. Because a dry sump does not need a large and deep oil pan to hold the oil under the engine, the main mass of the engine can be placed lower in the vehicle.
Dry sump lubrication systems are commonly used with high performance engines such as engines used in motorcycles, high end performance vehicles, racing vehicles, and aircraft. Dry sump lubrication systems include a supply of lubricating oil retained in a reservoir or oil tank separate from a sump portion of the crankcase. During operation of the engine, oil is pumped from the oil tank and is directed to bearings and other parts of the engine which are to be lubricated. Oil that is thrown from the crankshaft and bearings during the operation of the engine is received in the sump located in a lower part of the crankcase. The oil received in the sump is pumped back to the oil tank by a scavenge pump. However, the lubricating oil which is pumped from the sump contains a large quantity of air, which has been absorbed into the oil due to splashing of the oil during the lubricating process. Air is also absorbed into the oil as the oil is pumped from the sump by the scavenge pump. Absorbed air in the lubricating oil results in lowered lubricating efficiency of the oil. Some prior art dry sump lubricating systems have used castor oil as a lubricant, since the foaming property of castor oil is superior to that of mineral oil.
More commonly, a deaerator or air separator is used for deaerating the oil after it is pumped from the engine sump by the scavenge pump and before the oil is returned to the engine. The deaerator may include a cylindrical tank mounted in an upper tank portion of the oil tank in which the oil is sprayed tangentially against the inside surface of a cylindrical wall defining the cylindrical tank. Some of the entrained air is thereby separated from the oil by centrifugal force due to the rotating movement of the oil during passage of the oil along the inside surface of the cylindrical wall from an inlet to an outlet of the deaerator. Another type of air separator includes an internal baffle assembly disposed in the upper tank portion of the oil tank.
In either of the above arrangements, a feed hose from the oil tank assembly is routed to the bottom of the oil tank assembly where deaerated oil collects, while a return hose from the scavenge pump is routed to the top of the oil tank assembly where the deaerator is located.